import { useCallback, useEffect, useState, type SetStateAction } from "react";
import { useHostGlobal } from "./use-host-global";
import type { UnknownObject } from "./types";
/**
* React hook for persisting widget state on the MCP Apps host.
* State survives tool calls and is restored when the widget re-renders.
*
* @example
* const [state, setState] = useWidgetState({ count: 0, selectedId: null });
*
* // Update state (automatically syncs to host)
* setState(prev => ({ ...prev, count: prev.count + 1 }));
*/
export function useWidgetState<T extends UnknownObject>(
defaultState: T | (() => T)
): readonly [T, (state: SetStateAction<T>) => void];
export function useWidgetState<T extends UnknownObject>(
defaultState?: T | (() => T | null) | null
): readonly [T | null, (state: SetStateAction<T | null>) => void];
export function useWidgetState<T extends UnknownObject>(
defaultState?: T | (() => T | null) | null
): readonly [T | null, (state: SetStateAction<T | null>) => void] {
const widgetStateFromWindow = useHostGlobal("widgetState") as T;
const [widgetState, _setWidgetState] = useState<T | null>(() => {
if (widgetStateFromWindow != null) {
return widgetStateFromWindow;
}
return typeof defaultState === "function"
? defaultState()
: defaultState ?? null;
});
useEffect(() => {
if (widgetStateFromWindow != null) {
_setWidgetState(widgetStateFromWindow);
}
}, [widgetStateFromWindow]);
const setWidgetState = useCallback(
(state: SetStateAction<T | null>) => {
_setWidgetState((prevState) => {
const newState = typeof state === "function" ? state(prevState) : state;
if (newState != null) {
window.openai?.setWidgetState?.(newState);
}
return newState;
});
},
// eslint-disable-next-line react-hooks/exhaustive-deps
[]
);
return [widgetState, setWidgetState] as const;
}
